Genetic counseling: Developmental Delay and Mental Retardation
Developmental Delay and Mental Retardation Etiology *Cause unknown in about 50% of cases **Often multifactorial with genetic and environmental components **Low birth weight, prematurity, and perinatal complications may be associated - not known if they cause mental retardation or if factor causing these problems also caused MR *Approximately 2000 known genetic causes **Chromosomal abnormalities **Metabolic or endocrine disorders **Hereditary degenerative disorders **Hormonal deficiency **Hereditary syndromes or malformations *Acquired causes **Prenatal: infection, irradiation, or exposure to toxins **Perinatal: prematurity, anoxia, cerebral damage, or infection **Postnatal: brain injuries, anoxia, poisons, hormonal deficiencies, metabolic dysfunction, postimmunization encephalopathy, sociocultural, kernicterus, epilepsy *In United States, 1-3% of people meet cognitive and functional criteria Clinical Features *Not a medical or mental disorder *Affects developmental and cognitive abilities **Substantial limitations in functioning **IQ scores below 70 ***Mild MR: IQ range 50-55 to 70 ***Moderate MR: IQ range 35-40 to 50-55 ***Severe MR: 20-25 to 35-40 ***Profound MR: Below 20-25 **Majority of individuals with mental retardation have IQ scores of 55-69 ***Able to live independently or with support in group homes ***Less than 10% of all people with mental retardation have severe to profound impairments **May have limited ability to develop some adaptive skills ***Communication ***Home living ***Work ***Self-care ***Social/interpersonal skills ***Self-direction ***Functional academic skills ***Leisure ***Health and safety ***Use of community resources *Can affect abilities in key developmental areas **Language development **Visual and auditory perception and discrimination **Abstract problem solving *Onset must occur before age 18 Management options *No treatment or cure *Early intervention services **Provided by the county in Ohio to children between birth and age 3 **Studies show the earliest experiences in learning sets the pattern for later information processing **Begins with comprehensive developmental assessment ***May be performed here by CCDD or by private service ***Assessment used to develop intervention strategy *After age 3, school system provides special services **Develop an Individualized Education Plan (IEP) **Early education focuses on cognitive development and special services such as speech therapy **Later education may focus on developing life skills **Can attend school until age 21 *Adult services **Handled in Ohio by the Board of MRDD **Focuses on job training, vocational education **Community or group homes are available for semi-independent living Recurrence Risks *Can calculate a much more accurate risk if etiology is known *Other factors to consider: **Possibility of consanguinity **Whether one or both parents are affected **Developmental disabilities may be exacerbated by environmental factors ***Unsafe or unstimulating home environment ***Substandard health care ***Unadequate schooling or lack of services *Empiric risk figures when parents affected with mental retardation of unknown etiology **39.4% if both parents affected **7.8% if only father affected **19.6% if only mother affected (higher due to prevalence of X-linked inheritance for conditions such as Fragile X) Psychosocial Issues *Provision of adequate services *Burden of taking care of a child/adolescent/adult with mental retardation *Impact on siblings and other family members *Denial, grief, disappointment, or feeling of loss *Interruption of career goals, family routines, or plans for the future *Financial and insurance issues References *Milunsky, Aubry. Prevention of Genetic Disease and Mental Retardation. Philadelphia: W.B. Saunders Company (1975). Notes The information in this outline was last updated in 2001. This material has been imported fom the wikibook "Genetic counseling"[ http://en.wikibooks.org/wiki/Genetic_counseling] under the GNU Free Documentation License.